Rust inhibitors comprising lithium salts

ABSTRACT

THE LITHIUM SALTS OF HYDROCARBON-SUBSITUTED SUCCINIC ANHYDRIDE, WHEREIN THE HYDROCARBON SUBSITUENT IS AN ALIPHATIC HYDROCARBON GROUP HAVING ABOUT 9 TO ABOUT 30 CARBON ATOMS, ARE EFFECTIVE AS RUST AND CORROSION INHIBITORS IN LUBRICATING OIL COMPOSITIONS. THESE SALTS ARE RENDERED MORE OIL-SOLUBLE BY COMBINING THEM WITH ALKYL PHENOLS.

3,634,240 RUST INHIBITORS COMPRISING LITHIUM SALTS Rosemary OHalloran,Union, NJ., assignor to Esso Research and Engineering Company NoDrawing. Continuation-impart of application Ser. No. 798,123, Feb. 10,1969. This application Aug. 19, 1970, Ser. No. 65,316

Int. Cl. ClOm 1/24, 1/48 US. Cl. 252-323 R Claims ABSTRACT OF THEDISLOSURE The lithium salts of hydrocarbon-substituted succinicanhydride, wherein the hydrocarbon substituent is an aliphatichydrocarbon group having about 9 to about carbon atoms, are effective asrust and corrosion inhibitors in lubricating oil compositions. Thesesalts are rendered more oil-soluble by combining them with alkylphenols.

Related application This application is a continuation-in-part ofcopending application, Ser. No. 798,123, filed Feb. 10, 1969, nowabandoned.

BACKGROUND OF THE INVENTION Field of the invention Description of theprior art The prior art has taught the need for efiicient rustinhibitors in lubricating oils. The need is especially prevalent inengines which are infrequently operated and particularly in engineswhich are subject to extended storage in humid climates. These enginesexperience excessive rusting of cylinder walls, wrist pins and otherpolished working surfaces. Such rusting can be explained by the factthat moisture accumulates within the engine, penetrates the lubricatingfilm, and attacks ferrous surfaces. The attack is also aggravated byresidues of chlorine compounds and bromine compounds left from thecombustion of gasolines containing tetraethyl lead and a scavengingagent such as ethylene dibromide. The prior art has also shown the needfor efiicient corrosion inhibitors to prevent or reduce the depositionof lacquer or varnish-like coatings on the walls of the cylinders,piston rings, etc., and to prevent or reduce the corrosion of engineparts, bearings etc. An example of a specific purpose served by acorrosion inhibitors is the prevention of copper-lead hearing corrosion.

It is well known in the prior art that C C alkenyl succinic anhydridesand acids are good ashless rust inhibitors for motor lubricants. But (inashless formulation) they cause considerable copper-lead bearing weightloss.

It is also well known in the art that lithium salts ofhydrocarbon-substituted succinic acids having at least about 50aliphatic carbon atoms in the hydrocarbon substituent such as Cpolyisobutenyl succinic anhydride (conveniently designated PIBSA) areeffective rust and corrosion inhibitors in lubricating compositions.(See US. Pat. No. 3,351,552.) However, this and other prior artreferences teach that, when using a salt of a hydrocaratent icebon-substituted succinic acid, the size of the hydrocarbon substituentof the succinic compound appears to determine the effectiveness of theadditive in lubricating oils. Thus, the prior art is replete withstatements to the effect that it is critically important that saidsubstituent be large; that is, that it have at least about 50 aliphaticcarbon atoms in its structure that the molecular weight of thehydrocarbon substituent should be within the range of about 700 to about10,000. Because such salts have high molecular weight hydrocarbonsubstituents, a relatively higher weight percent active ingredientcontent in oil is required than would be necessary if shorter chainhydrocarbon succinic acid salts could be used. However, as indicated,salts of the shorter chain aliphatic-hydrocarbon-substituted succinicacids have heretofore not been used in lubricating oils because theypresent oil solubility problems.

SUMMARY OF THE INVENTION It has now been discovered that the lithiumsalts of C C aliphatic-hydrocarbon-substituted succinic anhydrides andacids (conveniently designated ASA) can be made more soluble inlubricating oils by combining them with a C C alkyl phenol. Thehydrocarbon substituents will be either alkyl groups or alkenyl groups.The lithium salts thus modified are not only excellent rust inhibitors,but also show marked resistance to Cu-Cb corrosion. A particularadvantage of the invention is that by making the lithium salts moreoil-soluble, it is possible to prepare liquid oil concentrates, whichgreatly facilitates blending operations when making finished lubricatingoil composi tions.

DETAILED DESCRIPTION The salts of this invention are prepared byreacting a C C ASA with a lithium base such as lithium oxide, hydroxide,carbonate or alkoxide. The product can be the full or half salt of theASA, both of which show excellent rust and corrosion inhibition.

The alkenyl-substituted or alkyl-substituted succinic acids andanhydrides used in forming the salts of this invention must have analiphatic hydrocarbon substituent containing at least 9 and up to about30 carbon atoms. Preferably, the substituent has 10 to 20 carbon atoms.Alkenyl-substituted acids and anhydrides are obtained by conventionalmethods known in the art which simply involve heating maleic anhydrideand an olefinic material together, usually in about equal molarportions. By way of example, a C -C alkenyl succinic acid anhydride canbe prepared by the condensation of maleic acid anhydride and a C Cfraction of propylene polymer by heating with agitation for 20 hoursunder pressure at a temperature of about 350 to 390 F. under gentlereflux. The reaction product is then allowed to cool and is fractionatedunder diminished pressure to remove unreacted polymer and low-boilingreaction products. The resulting alkenyl succinic acid anhydride canthen be employed directly to produce certain of the salts hereinafterdescribed. Alternatively, the anhydrides can be readily purchased as acommercial chemical commodity. In the present invention, either alkenylsuccinic anhydrides or the corresponding acids can be used and it is tobe understood that any general description involving the used of theanhydride is intended to encompass the use of the equivalent acid asWell and vice versa. Among the alkenyl-substituted succinic acids andanhydrides which can be used according to the present invention aredecenyl, tetradecenyl, hexadecenyl, octadecenyl, eicosenyl,hexaeicosenyl and octaeicosenyl succinic anhydride or acid, and mixturesthereof. A particularly preferred material is dodecenyl succinicanhydride (hereinafter referred to as DDSA) which can eadily be preparedby the addition of tetrapropylene to naleic anhydride.

In place of the alkenyl succinic acid or anhydride, the orrespondingsaturated acid or anhydride, or mixtures )f saturated and unsaturatedmaterials, can be used. Conersion of the alkenyl group to the alkylgroup is usually .ccomplished by hydrogenation to saturate the doubleIond, using procedures well known in the art. See US. at. 2,682,489.

In the reaction herein between the ASA and the lithium vase, thereaction temperature can vary from about 50 about 350 F., and preferablyranges from about 150 0 about 300 F. Usually the stoichiometric amountof ithium base necessary to prepare at least the half salt If thedicarboxylic hydrocarbomsubstituted succinic acid vill *be used,although as much as twice the amount of me needed to form the fuli saltcan be employed, in vhich case basic salts will be formed. Thus, themole atios of lithium base to ASA can vary, and preferably ange anywherefrom about 1:1 to about 4:1. In the most preferred embodiments of thisinvention, the mole atios range from about 1 :1 to about 2:1.

While it is possible to disperse the insoluble lithium alts of C -Calkenyl or alkyl succinic anhydrides or cids into lubricating oilcompositions with the aid of lispersing agents, it is much preferred towork with oil oluble additives as opposed to oil dispersible additives.urthermore, as a practical matter, it is preferred and u'edominantly thepractice to blend additives into lubriating compositions in concentrateform. Usually in a oncentrate, the weight percent of active ingredient'anges from about 10 to about 80 weight percent, for here is no economicadvantage in using concentrates raving less than .10 weight percentactive ingredient. Howver, if one attempts to prepare concentrateswherein the weight percentage of oil insoluble lithium salt of ASAgreater than 10, using dispersants, such cencentrates Jill form solidgels at ambient temperatures, thus preenting a number of disadvantagesin their handling in ubsequent blending operations.

Thus, it is a particular feature of the present invenion that bycombining the lithium salts of C -C ASA lilh a solubilizer, the saidlithium salts are rendered oil oluble to the extent that liquid oilconcentrates can be repared having as much as 50 weight percent oflithium alts.

There are a number of oxygen-containing compounds hich will solubilizelithium salts of aliphatic-hydrocaron-substituted succinic acids oranhydrides. Among 1ese are tall oil fatty acids and alcohols such asisoctanol and nonanol. However, all of these materials ave thedisadvantage of reducing or destroying the coper-lead corrosioninhibiting properties of the lithium alts. Of all the oxygen-containingmaterials that were Jund to be solubilizers, only the alkyl phenols madethe lthium salts soluble in lubricating oils without destroyig thecopper-lead corrosion inhibiting properties of the alts and allowed thepreparation of a stable liquid conentrate. The phenols used in thereaction mixture inlude alkyl phenols having a total of 5 to 30, andpreferbly 8 to 26, carbon atoms in their alkyl side chains and my bepolyhydric phenols containing more than one ring :ructure. The so-calledbis phenols may be used, also cyl phenols, amino phenols, acetyl phenolsand dialkyl henols. Thus, typical compounds include 2,2-bis-(2- ydroxy 3tert butyl 5 methylphenyl) propane, iethylamino phenols, benzyl aminophenols, acyl amino henols, for example, N-propionyl-p-aminophenol,acetyl henol, and their homologues. Condensation products of uch phenolswith aldehydes or ketones, e.g., formaldeyde and acetone, may also beused.

The preferred phenols are monoalkylated monohydroxy henols whosemolecular weights are between 150 and 00. Especially preferred aremonoalkylated phenols hav 1g 8 to 12 alkyl carbon atoms. Particularlyeffective compounds include p-octyl phenol, mixed nonyl phenols, mixeddodecyl phenols, and dihexyl phenol.

The phenol that is used to solubilize the ASA salts can be present whenthe lithium salt is made, or can be added later to the lithium salt.Reaction time of combining these components is not critical. The onlyrequirement is that the phenol be present while the temperature of themixture is at least as high as the melting point of the salt. Thus, thesolubilization which must be carried out while the salt is in liquidphase can be effected at a temperature range of about 300 to about 500F., and preferably at a temperature range of about 350 to about 450 F.

It is to be understood that the exact nature of the compositions formedupon the addition of the alkyl phenol has not been determined and, whilethey have been referred to as solubilized lithium salts, it is possiblethat a lithium phenate complex has been formed between the ASA, thelithium base, and the alkyl phenol or that some other undeterminedcompositional structure has resulted.

While experiments indicate that in the preferred embodiments of theinvention the mole ratio of salt to phenol will range from about 8:1 toabout 1:1, ratios ranging from about 15:1 to about 0.511 will in manycases also result in the desired oil soluble product.

It has also been found that if the C -C ASA is treated with sulfurbefore or after, but preferably before, neutralization andsolubilization, the resulting product shows no deterioration of Cu-P'b(over a base case containing detergent-inhibitor alone) and has theunexpected advantage of having even greater solubility, thus allowingthe manufacture of a 50% active ingredient concentrate with obviouslyimproved ease of handling.

Preferably phosphorus pentasulfide is used to promote the reaction ofthe acid or anhydride and sulfur. Alternatively, other sulfides, such asP 8 P48 and P 8 may be employed if desired. The molar ratio of ASA tosulfur to be used can range between about 120:1 and about 02:1, and thepresence of phosphorus sulfide in a molar ratio of ASA to phosphorussulfide ranging from about 72021 to about 1:1 will aid the reaction.Preferably the molar ratio of ASA to S will range from about 60:1 toabout 0.521 and the molar ratio of ASA to phosphorus sulfide will rangefrom about 150:1 to about 5:1. {In the most preferred embodiments ofthis invention, the molar ratio of ASA to S will range from about 15:1to about 1:1, and the molar ratio of ASA to phosphorus sulfide willrange from about :1 to about 10:1. In the reaction herein between theanhydride, the sulfur and the phosphorus sulfide, the reactiontemperature can vary from to 450 F., preferably from 250 to 350 F., andthe time can vary from 0.1 to 10 hours, preferably from 0.5 to 2 hours.The order of addition of P 8 and sulfur is not important and P 5 can beadded first, S can be added first, or they can be added simultaneously.

This invention contemplates the use of 0.01 to 50 Weight percent of theproducts of the present invention in oil compositions. As stated above,the lithium salts of the present invention, in combination with an alkylphenol, are useful as antirust additives in lubricating oils and whencombined with a lubricating oil will form homogeneous liquid lubricatingoil compositions which are stable at ambient temperatures. When used asantirust additives, they can be incorporated in lubricating oilcompositions in concentrations within the range of from about 0.01 toabout 10 weight percent active ingredient, but will ordinarily be usedin concentrations of from about 0.01 to about 5 weight percent.Preferably, they will be used in concentrations ranging from about 0.1to about 1 weight percent active ingredient.

The lubricating oils to which the additives of the invention can beadded include not only mineral lubricating oils, but synthetic oilsalso. The mineral lubricating oils may be of any preferred types,including those derived from the ordinary paraffinic, naphthenic,asphaltic, or mixed base mineral crude oils by suitable refiningmethods. The synthetic oils include synthetic hydrocarbon lubricatingoils, as well as dibasic acid esters such as di-2-ethyl hexyl sebacate,carbonate esters, phosphate esters halogenated hydrocarbons,polysilicones, polyglycols, glycol esters such as C oxo acid diesters oftetraethylene glycol, and complex esters, as for example the complexester formed by the reaction of 1 mole of sebacic acid with 2 moles oftetraethylene glycol and 2 moles of 2-ethyl hexanoic acid.

While the lubricant compositions herein described are primarilydesignated as internal combustion engine crankcase lubricants, theadditives of the invention may also be employed in other oilcompositions, including turbine oils, various industrial oils, gearoils, hydraulic fluids, transmission fluids and the like.

It is within the contemplation of this invention to prepare easilyhandled liquid additive concentrates in which the concentration ofadditives is greater than would normally be employed in a finishedlubricant. These concentrates may contain in the range of from to 50% ofadditive on an active ingredient basis, the balance being mineral oil.Such concentrates are convenient for handling the additive in theultimate blending operation into a finished lubricating oil composition.The additive concentrates can be made up simply by combining the lithiumsalts and alkyl phenol of the present invention in a suitable mineraloil medium. The additive package can also include other additives thatare intended for use along with the additives of the invention in afinished lubricant. Such additives include, for example, detergents anddispersants of the ash-containing or ashless type, oxidation inhibitingagents, viscosity index improving agents, pour point depressants,extreme pressure agents, color stabilizers and antifoam agents. Typicalexamples of additives serving these purposes are known to those skilledin the art.

Alternatively, although not preferably, the alkyl phenol and the lithiumsalt can be combined in any aliphatic or aromatic hydrocarbon with aboiling point of about 400 F. or higher, e.g., ortho-cresol or cetane,which, can then be boiled off to leave a readily soluble additive insolid form.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples willserve to illustrate methods of preparing the compositions of thisinvention and include preferred embodiments of said invention.

EXAMPLE 1 Part A A solution of 90.4 grams of DDSA (dodecenyl succinicanhydride) in 540 grams of a solvent-refined naphthenic oil having aviscosity at 210 F. of 37 SUS (hereinafter referred to as Oil A) isheated at 320 F. and a solution of 16.8 grams of lithium hydroxidemonohydrate dissolved in 40 grams of boiling water is added over aone-hour period with mixing. The product, having a lithium to DDSA molarratio of about 1:1; solidifies on cooling into a loose grainy grease.

Part B The product of Part A is reheated to 380 F. and grams of mixednonyl phenols are added with mixing. The product having an ASA to alkylphenol molar ratio of about 3.421 is allowed to cool and is observed toremain in liquid form. The mixed nonyl phenols are prepared byalkylating phenol with tripropylene to produce a product comprisingabout 65 to 70 weight percent nonyl phenol and to weight percent dinonylphenol. The mixture is hereinafter referred to as nonyl phenol FromExamples 1(A) and 1(8) it can be seen that an alkyl phenol willsolubilize an otherwise soluble lithium salt of DDSA and that an 18%concentrate of lithium salt and phenol complex in oil can be prepared bythis procedure.

EXAMPLE 2 There is added 20 grams of octyl phenol to a solution of 45.2grams of DDSA in 540 grams of Oil A. A solution of 16.8 grams of lithiumhydroxide monohydrate dissolved in 40 grams of water is then added overa 45 minute period with mixing at a temperature o-f 280 F. untilessentially all the water is boiled off. The temperature is thenelevated over a 30-minute period to 400 F. to melt the salt. Uponcooling, the product, a 10% concentrate of lithium salt and phenolcomplex in oil, is obtained as a clear viscous liquid. The lithium salthas a lithium to DDSA molar ratio of about 2:1.

EXAMPLE 3 The procedure of Example 2 is repeated, substituting, fordodecenyl succinic anhydride, dodecyl succinic anhydride obtained byhydrogenating the dodecenyl succinic anhydride.

EXAMPLE 4 A solution of 90.4 grams of C ASA (prepared by heating maleicanhydride and octaeicosenyl alpha olefin) in 540 grams of Oil A isheated to 320 F. and a solution of 8.4 grams of lithium hydroxidemonohydrate dissolved in 40 grams of boiling water is added over a30-minute period with mixing. The temperature is raised over a 45-minuteperiod to 400 F. and 10 grams of nonyl phenol is added with mixing. Theproduct on cooling remains in liquid form, and is an additiveconcentrate suitable for lubricating oil blending operations.

EXAMPLE 5 A solution of 90.4 grams of C ASA (prepared from maleicanhydride and eicosenyl alpha olefin) in 540 grams of Oil A is heated at320 F. and a solution of 11.2 grams of lithium hydroxide monohydratedissolved in 40 grams of boiling water is added over a one-hour periodwith mixing. Thereafter, 20 grams of C alkyl phenol is added with mixingand the temperature is raised over a 30- minute period to 380 F. Uponcooling the product concentrate appears as a clear viscous liquid.

EXAMPLE 6 A solution of 123 grams of DDSA in 730 grams of Oil A isheated to 300 F. and a solution of 23 grams of lithium hydroxidemonohydrate dissolved in 40 grams of boiling water is added over a45-minute period with stirring. The temperature is raised to 375 F. and25 grams of mixed nonyl phenol is mixed into the solution. The solutionis cooled to 350 F. and 27 grams of sulfur is added with vigorous mixingover a 15-minute period. The solution is then blown with nitrogen for 10minutes and allowed to cool. The product analyzes 0.76% sulfur.

EXAMPLE 7 After grams of DDSA has been heated to 280 F one gram ofsulfur is added over a 15-minute period, followed by the addition of onegram of P 8 with mixing over a 30-minute period. After reheating theresulting product to 280 F., grams of Oil A and 18 grams of lithiumhydroxide monohydrate dissolved in 40 grams water are added over aone-hour period with mixing. Then 20 grams of nonyl phenol is added andthe temperature is raised over a one-hour period to about 400 F. Theproduct is stirred until it is a uniform liquid. The product uponcooling needs no filtering and is observed to be a red brown, clear,viscous liquid.

EXAMPLE 8 A blended base oil was prepared by blending at F. (1) 2.87weight percent of an oil composition comprising 70% of an amidecondensate of polyisobutenyl propionic acid and triethylene pentarnine(see preparation in Example 1, U.S. Pat. 3,364,130); (2) 0.95 weightpercent of an oil composition consisting of 25 weight percent of ahydrocarbon lubricating oil and 75 weight percent of 7 zinc dialkyldithiophosphate prepared from a mixture If 65% isobutyl alcohol and 35%primary amyl alco- [018; (3) 76.94 weight percent of a high viscosityindex, IhI101-XtfaCtd, solvent-dewaxed lubricating oil distil- 8 tion asthe concentration of active ingredient is reduced to one percent. Thelithium salts of PIBSA have been found to be unacceptable as rustinhibitors at concentrations below one percent. Thus, the lithium saltsof ate having a viscosity at 100 F. of 325 SUS; and (4) 5 this inventioncan be used at much lower concentrations 9.24 weight percent of adewaxed, deasphalted paraffinic than are required with the prior arthigher molecular esidual bright stock. weight lithium salts in order toobtain satisfactory oil The base oil, and compositions consisting of thebase compositions. Iil to which difierent weight percent activeingredient It is also to be noted that, while 0.5 wt. percent of mountsof lithium salts were added, were tested for rust DDSA causes acopper-lead weight loss of over 440 mg, uhibition and corrosion ofcopper-lead bearings. For rust the use of the same concentration of alithium salt of the uhibition a variation of the General Motors MS testdodecyl succinic acid treated with sulfur and P 5 shows eries was used,employing a sequential MSIIA+2 engine no increase in copper-lead weightloss over that found in nerit test. The MSIIA-i-Z engine test entailsrunning the the base oil without any antirust additive. egular MSIIA lowtemperature cycle plus 2 hours of he MSIIIA high temperature cycle, thendisassembling EXAMPLE 9 nly the parts to be rust rated. The enginecrankcase Laboratory m ip xi i n tests w r 3 then drained, filled withnew test oil (plus dummy rust run on the blended base oil described inExample 8 and est parts) and run to flush the system of all the oil andon the base oil plus various additives to test the efiect esidue fromthe fir t run, Then, new arts and fre h of these additives on oxidation.In this test, 40 gram est oil are placed in the engine for the next run.An Samples Were P p Consisting of the base Oil into /ISIIB+2 test wasalso employed which entails running which different weight percentagesof different additives b regular MSIIB cycle plus 2 hour of the MSIIIBhad been incorporated. Then, 2.5 grams of iron filings, ycle. The MSAseries of test is described in ASTM a 19 piece of No. 14 gauge copperwire and a sanded lpecial Technical Publication 315C and the MSB seriesaluminum strip (12" x A" x were added to each described in ASTM SpecialTechnical Publication composition as catalysts. Air at the rate Of 25CC. per 15X. To test corrosion the standard sequential L-38 minute Wasbubbled through the Sample, Whose p Iu-Pb bearing mg. weight loss testwas employed. The ature was maintained at 300 F. At the end of fivedays, ollowing Table I shows the data obtained. Except as hneutralilation number 0f the used, .oted below, the various lithiumsalts were added as OXidiZed, Oil w d t rmined- Table II shows theoncentrates, however, the weight percentages in the fol- ASTM-D-974total acid number data obtained from owing tables are on the basis ofpercent active ingredient these tests. 1 the total composition. Thenotation Li/2 signifies 2. TABLE H alf lithium salt, and Li/2 P'IBSAsignifies a half lithium IMOT t t 5d 3000 F C F M t I t no alt ofpolyisobutenyl succinic anhydride, wherein the 1 0X1 awn ess ays/caayss'anj m/mm olyisobutenyl group had an average of 50 carbon atoms.Total acid Weight number/5 days TABLE I.FULL-SCALE ENGINE TEST DATAAdditive percent (ASTM-D-QH) Active 4.7 ingredient, 0. 3 6. 3 weightMSIIA-l-Z L-38 Cu-Pb 40 Li/Z DDSA1 0.3 4.9 dditive percent rust meritBWL (mg.) il DDSA 1 0.16 3. 7 Li/Z DDSA+CD phenol 2 0. 3 2.8 'one 5.4 65'DS 0.6 8. 7 454 1 Product of Example 1, Part A. i/2 PIBSA 1.8 9.1 2Product of Example 1, Part B.

{51388210- ii'g lii Table 11 illustrates that the additives of thisinvention gggiijjj 9- 31% 23 do not increase thermal oxidation atextreme tempera- DD A+Cr phenol 165 tures and, in fact, the lithium saltand the alkyl-phenol- 3,2:$Eg3$%1 57 modified salt actually reduceoxidation as measured by P i g 60 the total acid number.

An additional advantage of this invention is that even j EXemp1e1,PartA-the P S -S-treated lithium salt of DDSA, for instance,

roduet of Example 2. ap fE 1 1 1 tB has a much lower ash level when usedin an amount ProductOfEXemDle suflicient to give good rust protectionthat does a corre- The data presented in Table I show that the oil solu-Sponding conventional overbased calcium sulfonate. Said lc combinationsof lithium salt and alkyl henol are as overbased calcium sulfonate Whichis one Of the mOSt ood rust and corrosion inhibitors as the oilinsoluble pt d rust inhibit rs in use today in motor oils is thium halfsalts of DDSA, which were incorporated into used in the form of amineral oil concentrate of over- 1e oil compositions for testingpurposes through heating, based calcium sulfonate repared from syntheticalkyl igorous mixing and the use of a dispersant (an amide aromatics ofabout 420 molecular weight and contains ondensate of polyisobutenylpropionic acid and tetraabout 30% calcium sulfonate and about 25%calcium thylene pentamine; see British Pat. 1,075,121). This carbonateand has a Total Base Number of about 300 emonstrates that none of thedesirable porperties of the (mg./KOH/g.). thium salts of C C alkenylsuccinic acids or a-nhydrides It is estimated that about 3.5 wt. percentof this conre impaired by rendering them oil soluble in accordancecentrate would be necessary in order to give the same ith the presentinvention. The data in Table I show level of performance in the MSIIB+2test as did 0.5% lso that, while the lithium salts of PIBSA are goodrust AI of Li/Z P S -S-DDSA+C phenol. The difference nd corrosioninhibitors, these higher molecular weight between the ask levels ofthese two additives is comthium salts undergo a marked decrease in rustinhibipared in Table III.

TABLE III Blend Percent Weight Percent Percent sulf. percent Percentsulf. Additive Metal ash ash add. cone. ash ash Overbased calciumsulfonatc 12.0% (2a.... 17 40 3. 5 0, 600 1, 400 Li/2 PgSfi-S-DDSAd-CPhenol 1.2% Li... 2.6 9. 7 1. 0 0.026 0. 096

1 Product of Example 7.

While particular embodiments of this invention are shown in theexamples, it will be undertsood that the invention is obviously subjectto the variations and modifications disclosed above without departingfrom its broader aspects. Accordingly, it is not intended that theinvention be limited to the specific modifications which have been givenabove for the sake of illustration, but only by the appended claims.

What is claimed is:

1. An oil-soluble composition comprising:

(a) a corrosion inhibiting proportion of a lithium salt of analiphatic-hydrocarbon-substituted succinic acid having from about 9 toabout 30 carbon atoms in the aliphatic hydrocarbon radical; and

(b) an oil-solubilizing proportion of an alkyl phenol having a total ofabout to about 30 alkyl carbon atoms.

2. The composition of claim 1 wherein the molar ratio of lithium tohydrocarbon succinic acid in component (a) ranges from about 1:1 toabout 4:1 and the molar ratio of component (a) to (b) ranges from about15:1 to about 0.5: 1.

3. The composition of claim 1 wherein the aliphatic hydrocarbonsubstituent of said substituted succinic acid has from about to about 20carbon atoms and said alkyl phenol has from about 8 to about 26 alkylcarbon atoms.

4. The composition of claim 3 wherein said hydrocarbon substituent isdodecenyl and wherein said alkyl phenol is nonyl phenol.

5. A lubricating oil composition comprising:

(a) a major proportion of an oil of lubricating viscosity;

(b) a minor corrosion inhibiting proportion of a normally oil insolublelithium salt of an aliphatic-hydrocarbon-substituted succinic acidhaving from about 9 to about 30 carbon atoms in the aliphatichydrocarbon radical; and

(c) a minor proportion of an alkyl phenol in an amount sufficient torender said lithium salt soluble in said oil.

6. The composition of claim 5 wherein the molar ratio of lithium tohydrocarbon-substituted succinic acid ranges from about 1:1 to about4:1, the molar ratio of component (b) to (c) ranges from about 0.511 toabout :1 and the combination of components (b) and (c) represents about0.01 to about 5 wt. percent of the total lubricating composition.

7. The composition of claim 5 wherein the hydrocarbon substituent ofsaid hydrocarbon succinic acid has from about 110 to about carbon atomsand said alkyl phenol has from about 5 to about 30 alkyl carbon atoms.

8. The composition of claim 7 wherein said hydrocarbon substituent isdodecenyl and wherein said alkyl phenol is nonyl phenol.

9. A process for preparing an oil-soluble composition comprising:

(a) contacting a lithium salt of an aliphatic-hydrocarbon-substitutedsuccinic acid having from about 9 to about 30 carbon atoms in thehydrocarbon radical with an alkyl phenol in an amount suflicient torender said lithium salt soluble in oil; and

(b) heating the mixture to a temperature at least as high as the meltingpoint of the lithium salt.

10. The process of claim 9 wherein said temperature is in the range ofabout 300 F. to about 500 F. and the molar ratio of the lithium salt tothe alkyl phenol is from about 0.5:1 to about 15:1.

10 11. The process of claim 9 wherein the hydrocarbon radical has fromabout 10 to about 20 carbon atoms and the alkyl phenol has about 5 toabout 30 alkyl carbon atoms.

12. The process of claim 11 wherein said hydrocarbon radical isdodecenyl and wherein said alkyl phenol is nonyl phenol.

13. The process of claim 9 comprising the additional subsequent step ofadding sulfur wherein the molar ratio of hydrocarbon-substitutedsuccinic acid to sulfur ranges from about 120:1 to about 02:1 and saidcombination with sulfur takes place at a temperature in the range ofabout F. to 450 F.

14. The process of claim 9 wherein the lithium salt is the salt of analkenyl succinic acid which, prior to salt formation, has been reactedwith from about i to about 5 moles of sulfur per mole of said acid oranhydride thereof at a temperature in the range of about 100 F. to 450F.

15. The process of claim 14 wherein the combination of alkenyl succinicanhydride or acid and sulfur has been carried out in the presence of aphosphorus sulfide, the molar ratio of alkenyl succinic acid to S rangesfrom about 15 :1 to about 1:1 and the molar ratio of alkenyl succinicanhydride or acid to phosphorus sulfide ranges from about 72021 to about1:1.

16. A process for preparing an oil-soluble composition comprising:

(1) contacting (a) an aliphatic-hydrocarbon-substituted succinicanhydride or acid having from about 9 to about 30 carbon atoms in thealkenyl radical, with (b) an alkyl phenol; and then (2) combining theproduct of step (1) with (c) a lithium base, at a temperature in therange of about 300 F. to 500 F.

17. The process of claim 16 wherein the molar ratio of component (a) tocomponent (b) ranges from about 0.521 to about 15:1 and the molar ratioof component (c) to component (a) ranges from about 1:1 to about 4: 1..

18. The process of claim 16 wherein the hydrocarbon radical has fromabout 10 to about 20 carbon atoms and the alkyl phenol has about 5 toabout 30 carbon atoms.

19. The process of claim 18 wherein said hydrocarbon radical isdodecenyl and wherein said alkyl phenol is nonyl phenol.

20. A lubricating oil composition as in claim 5 wherein component (b)has been reacted with sulfur wherein the molar ratio ofhydrocarbon-substituted succinic acid to sulfur ranges from about 12021to about 0.221 and said combination with sulfur takes place at atemperature in the range of about 100 F. to 450 F.

References Cited UNITED STATES PATENTS 2,733,235 1/1956 Gross et al.25232.7 X

2,980,615 4/1961 Morway et a1 25241 3,351,552 11/1967 Le Suer 252413,485,858 12/1969 Gee et al. 260485 X DANIEL E. WYMAN, Primary ExaminerW. H. CANNON, Assistant Examiner US. Cl. X.R.

